The present embodiment relates to fusing of printed media. It finds particular application in conjunction with an integrated printing assembly in which marked media from a plurality of marking devices is directed to an addressable fusing system for selectively applying a secondary fusing treatment to the media and will be described with particular reference thereto. However, it is to be appreciated that the present embodiment is also amenable to other like applications.
In a typical xerographic marking engine, such as a copier or printer, a photoconductive insulating member is charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member, which corresponds to the image areas contained within the document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing material. Generally, the developing material comprises toner particles adhering triboelectrically to carrier granules.
The developed image is subsequently transferred to a print medium, such as a sheet of paper. The fusing of the toner onto paper is generally accomplished by applying heat to the toner with a heated roller and application of pressure. In multi-color printing, successive latent images corresponding to different colors are recorded on the photoconductive surface and developed with toner of a complementary color. The single color toner images are successively transferred to the copy paper to create a multi-layered toner image on the paper. The multi-layered toner image is permanently affixed to the copy paper in the fusing process.
Another approach employed to fuse toner to paper is to apply a high-intensity flash lamp to the toner and paper in a process known as “flash fusing.”
The fusing process serves two functions, namely to attach the image permanently to the sheet and to achieve a desired level of gloss.
Systems which employ several small marking engines are now being developed. These systems enable high overall outputs to be achieved by printing portions of the same document on multiple printers. Such systems are commonly referred to as “tandem engine” printers, “parallel” printers, or “cluster printing” (in which an electronic print job may be split up for distributed higher productivity printing by different printers, such as separate printing of the color and monochrome pages). These systems have been designed primarily for the office market. As xerographic marking engines are now used for a variety of different applications, the requirement for printing on media of varying substrate weight and surface roughness has increased. Coated stock is widely used in the graphics art industry, which increasingly relies on xerographic marking engines.
However, current xerographic marking engines are generally optimized for a particular type of paper and thus may be unable to fuse other substrates without a significant slowing in productivity. Fusing tends to impart curl to the paper, which can cause paper jams downstream of the fuser. Additionally, paper jams and printer damage can occur when the paper finish is not fully compatible with the fusing process. The fusing devices often have a limited lifetime because they are unable to maintain the high surface smoothness required for high gloss levels at typical fuser operating temperatures.